基于双针光纤探头改进的破碎波卷入气泡尺寸测量方法研究

Methodology of an improved technique for the bubble size measure in breaking waves using dual-tip optical fiber probe

基于双针光纤探头(D-OFP)的气液两相流测量方法可实现气泡粒径、弦长、运动速度、含气率等参数测量。目前,D-OFP已广泛应用于环境工程和石油化工等领域,但由于破碎波卷入气泡形状的不规则性及运动复杂性等特点,若直接将D-OFP用于破碎波卷入气泡尺寸测量,测量的精度和可靠性将有所降低。为克服上述不足,该文从D-OFP测量气泡尺寸的原理出发,着重分析了气泡侧向运动产生的测量误差,得出结论:当气泡运动方向与探头主轴方向夹角小于10o时的测量结果是准确合理的。并提出了基于双针光纤探头(D-OFP)改进的四针光纤探头(F-OFP)测量法,通过建立F-OFP数学模型,推导出了F-OFP多维度测量破碎波卷入气泡尺寸的基本公式,论证了F-OFP多维度测量破碎波卷入气泡的可行性,为破碎波卷入气泡尺寸分布研究提供了理论依据。

Gas-liquid two-phase flow parameters such as bubble size, bubble chord lengths, bubble velocity and void fraction can be measured by dual-tip optical fiber probe （D-OFP） which has been used in the environmental engineering, chemical industry area. However, if the measurement scheme used in above-mentioned area was adopted for the bubble sizemeasurements in breaking waves, the accuracy is reduced due to varied bubble shapes and irregular bubble motion caused by breaking waves. According to the detecting theory of D-OFP, the error of D-OFP measurement has been calculated. It is concluded that the result is reasonable when the angle between the bubble velocity vector and the probe＇s axial direction is less than 10°, and the four-tip optical fiber probe （F-OFP） based on D-OFP is suggested to realize bubble size measurement. In this paper, the basic equations for F-OFP by establishing mathematical model are derived, and the feasibility of bubble size measurements in breaking waves using F-OFP is authenticated. This work provides theoretical basis to bubble size measurements in breaking waves.